The hydrosilation of allyl chloride and related compounds have previously been catalyzed by platinum- or rhodium- containing compounds. For instance, the use of platinum containing hydrosilation catalysts is disclosed in U.S. Pat. Nos. 2,823,218, 3,814,730, 3,715,334, 3,516,946, 3,474,123, 3,419,593, 3,220,972, 3,188,299, 3,178,464, 3,159,601, German Patent No. 1,165,028 and published U.K. Patent Application No. 2,019,426A. Hydrosilation over chloro-rhodium compounds has been disclosed in U.S. Pat. Nos. 3,296,291 and 3,564,266. However, the yields obtained through the use of these catalysts are typically low, i.e., 40 to 70 percent. It is believed that these low yields are attributable to the existence of competing reduction reactions. For example, the addition of trichlorosilane to allyl chloride over a platinum catalyst results in the following two reaction pathways: ##STR1##
It has been reported in Zhurnal Obshchei Khimii, Vol. 44, No. 11 pp. 2439-2442 that the rate of the above reduction reaction increases appreciably as the halogen atoms of the silane are replaced with organic moieties presumably due to steric factors. For example, the reaction of trimethoxysilane with allyl chloride over a chloroplatinic acid catalyst produces 3-chloro-propyltrimethoxysilane in yields of less than 40%. Major by-products generated through the reduction reaction are trimethoxychlorosilane and propylene. The increased rate of the competing reduction reaction is thought to be responsible for lower yields of the desired hydrosilation product.
Accordingly, the development of a hydrosilation process which effectively generates halopropylalkoxysilanes and halopropylalkylalkoxysilanes from alkoxysilanes and alkylalkoxysilanes, respectively, in yields above those realized through the use of the processes of the prior art is highly desirable. Applicants have met this goal through the development of the instant process which is capable of producing yields in excess of 75 percent. These improved product yields realized through the instant process are further quite unexpected in view of the literature which discloses that iridium-containing catalysts are ineffective in the hydrosilyation of 1-olefins, (see, for example Iridium Complexes as Hydrosilyation Catalysts, Journal of Molecular Catalysis, 29 (1985) p. 60.)